In recent years the problem of abandoned wells in many areas of this country, particularly in the Midwest, has increased dramatically. Many years ago, the vast majority of the farms in operation in the Midwest were comparatively small, with each farm having its own well to provide for the individual farmer's water needs. However, due to the increased cost of farm machinery and other materials which are needed to adequately farm the land, many of these farms have been consolidated into larger and more efficient units. Since in many cases only one water system is needed to operate these larger farms, a large number of wells have become abandoned and in some cases polluted due to neglect.
If these abandoned wells are not adequately sealed, not only does the water contained therein become polluted, but also these wells pollute the water in adjoining operational wells. The abandoned wells can pollute these operational wells because the wells are usually connected by underground rivers or streams. Pollutants can enter these subterranean waterways by flowing down the unattended wells thereby polluting the water source used by functional wells in the immediate area.
Moreover, in more recent years many wells have become unsafe because of ground water contamination due to overuse of various types of pesticides including insecticides and herbicides, and in some sites mine acid run off, mine tailings contamination and/or even radioactive waste pollution. The underground waters, which can become polluted by spillage into abandoned wells or vice versa, service countless numbers of irrigation systems. If the water in those systems becomes polluted, crops cannot be safely produced and the soil can be permanently ruined. Furthermore, these underground rivers or streams can empty into above-ground rivers and streams thus polluting these water sources, also.
In addition, there is a continuing problem, particularly in the Midwest, of the ravages of flood damage which can pollute wells which are still in working order. Another problem in regard to abandoned wells is the danger of someone accidently falling into such a well thereby creating great risk of bodily injury or death.
Due to the great depth of some of these wells, and the fact that the bottom of the well shaft opens directly into the water source, it is quite impractical and nearly impossible to merely pour concrete or other hardenable substances into the well shaft to seal the well without first implanting a base structure in the shaft of the well. This base structure serves as a support for the hardenable material, and since the base is situated at a reasonably close distance to the top of the well, only a manageable amount of concrete need be used for filling the cavity formed between the base and ground level.
A device for solving these problems is shown in the Freiburger U.S. Pat. No. 3,995,694 which discloses an inflatable well seal using a releasable coupling. Such patent (also see attached FIG. 4) shows such a coupler 24 threaded internally at one end to fit a standard pipe thread which is on the outer surface of a valve stem 22 while the other end of the coupler 24 is threaded on the outside surface to engage an air hose 34 through the use of a standard inwardly threading coupling element 23 connected to the air hose 34. A gasket 59 is provided to ensure a tight fit between the stem 22 and the coupler 24. This coupler is fashioned of a plastic material well known in the art which can be constructed so that it breaks along a shear zone 26 of reduced thickness at predetermined internal pressure of the inflatable bag 20 such as 100 psi. At this pressure, the inflatable bag 20 will completely seal the well shaft. The coupler 24 contains a plurality of air holes 46 which allow the air to pass from the air hose 34 to the inflatable bag 20, through an orifice 54 located in the inflation valve stem 22.
A movable valve pin 42, which may be made of metal, is provided in the valve stem 22 which opens and closes orifice 54 thereby enabling the bag 20 to be filled with air and, when coupler 24 breaks, ensuring that air contained in the bag does not escape to the atmosphere but would remain in the bag 20. The valve pin 42 contains a substantially conical valve head 48 with the base portion 49 facing the interior of inflatable bag 20. The exterior surface 47 of the valve head 48 is adapted to be operatively engages with a valve seat 50 disposed on an annular flange which encircles the interior of valve stem 22. When the valve head 48 abuts against the valve seat 50, no air can enter or exit from the bag 20, but when the head 48 is not in contact with the seat 50, air may enter the bag 20 through orifice 54.
Coupler 24 also contains a valve pin 28 having a substantially cylindrical head 29. Valve pin 42 also contains a substantially cylindrical valve head 43 which cooperates with the valve head 29 of valve pin 28. When the coupler 24 is connected to the inflatable bag 20, the valve head 29 of the coupler 24 depresses valve head 43, thereby forcing the valve head 48 away from the valve seat 50. A compression spring 52 encircles the upper portion 56 of valve pin 42 between the head 13 of the valve pin 42 contained in valve stem 22 and the top portion 58' of flange 51. Therefore, before valve head 48 can be dislodged from valve seat 50, the force of this spring 52 must be overcome.
FIG. 5 attached depicts an automatically releasable coupler according to the an alternative embodiment of the Freiburger U.S. Pat. No. '694. This coupler 62, screw joined to the coupling element 23, is constructed without the shear zone 26 of coupler 24, but instead utilizing a pair of shear pins 60. A number of holes, corresponding to the number of shear pins used, are drilled or otherwise fashioned in the valve stem 22 and coupler 62 so that they align with one another. Therefore, the shear pins 60 provide for the attachment between the valve stem 22 and the coupler 62 and therefore no threading is between the valve stem 22 and the coupler 62 is needed for this connection. The shear pins 60 are then inserted into these holes thereby joining the stem 22 to the coupler 62. Thereafter, when the entire device is lowered into the well, these pins 60 will rupture when the internal pressure of the inflatable bag 20 reaches a predetermined level thereby releasing the coupler 62 from the stem 22.
The use of these constructions enables both the air hose 34 and the coupler 62 to be recovered and reused, but not without some difficultly for installation, and some possible damage upon removal thereof. Moreover, these constructions are more expensive than desirable because of the need to provide a threaded connection between the coupling element 23 and the coupler 24 or 62 so that the remnant of the coupler 24, 62 can be unscrewed and discarded after use, so the coupling element 23 can be reused.